What was the role of the sterile filter paper disc soaked in sterile distilled water in the experiment?

The sterile filter paper disc soaked in sterile distilled water serves as a negative control in the experiment. In microbiological experiments, a negative control is crucial as it helps to establish a baseline to compare the effects of the experimental treatments. By using sterile distilled water, the disc does not introduce any nutrients or antimicrobial agents that could influence bacterial growth. This allows researchers to determine if the observed bacterial growth or inhibition is due to the specific conditions being tested rather than outside factors.

In experiments involving bacteria, having a negative control is essential for validating the results, as it ensures that any changes in bacterial behavior can be attributed directly to the treatments applied. The presence of the sterile disc allows researchers to assess the effects of various substances while ensuring that any growth observed is not due to the presence of moisture or other uncontrolled variables.